The object of the invention are agents for the oxidative dyeing of hair, characterized by containing as coupling substances derivatives of 1,2 methylenedioxybenzene.
Oxidative colorants have obtained essential importance in the field of hair dyeing. The coloration results herein by a reaction of certain developing substances with certain coupling substances, in the presence of a suitable oxidating agent.
1,4-diaminobenzene, 2,5-diaminotoluene and p-aminophenol are used in particular as developing substances. Mention is to be made of resorcin, 4-chlororesorcin, .alpha.-naphthol, m-aminophenol and derivatives of m-phenylenediamine as preferably used coupling substances.
Oxidative colorants used in the dyeing of human hair must satisfy numerous special demands. They must be unobjectionable as to toxicology and dermatology, and allow dyeing to the desired intensity. It is furthermore required that a wide range of different color nuances will be obtained by the combination of suitable developing and coloring components. Furthermore, the resulting coloring should, to a good degree, be fast to light and resistant to permanent wave treatment, acids, and rubbing. Such hair coloring must, at any rate, remain stable against the influence of light, rubbing, and chemical agents for a period of at least 4 to 6 weeks.
The multitude of requirements put forward can, however, not be fully satisfied by oxidative hair dye agents as presently used, and also not by initial coloring stages as recently recommended, such as, for instance, derivatives of pyrimidine.
Endeavoring to obtain an improvement in the toxicological and dermatological aspects relative to agents for the oxidative dyeing of hair based on the developing substances 1,4-diaminobenzene and 2,5-diaminotoluene, attempts are being made at the present time, to increasingly substitute these developing substances by p-aminophenol which is more compatible physiologically. Hair dyeing agents on the basis of p-aminophenol in combination with known couplers can, however, neither produce natural color tints nor can an adequate color intensity be attained. Thus, substitution of, respectively,1,4-diaminobenzene or 2,5-diaminotoluene,by p-aminophenol,has hitherto been possible only in exceptional instances.
The task has therefore been posed to find suitable coupling substances which in combination with the physiologically advantageous developing substance p-aminophenol, will satisfy the requirements regarding naturalness and intensity of the attainable colorations, whilst maintaining the physiological advantages.